During the 301st live stream, a business owner who manufactures plastic molds asked: For plastic molds with small pillars, is 2344 or S136 a better choice?
Plastic molds with small pillars are essentially molds with bosses. During the injection molding process, these bosses are subjected to compressive forces, so the material must meet requirements for both toughness and strength. Molds of this type generally require hardened and tempered steel.
2344 is a medium-carbon hot-work die steel (4Cr5MoSiV1) with a carbon content of 0.38%. Medium-carbon steels offer good toughness. Additionally, since hot-work die steels are generally of high metallurgical quality, 2344 can achieve a hardness of 50 HRC, providing sufficient strength. Combined with its good toughness, this helps mitigate the risk of small pillars breaking.
S136 is a 4Cr13-type stainless steel. Although it also has a carbon content of 0.38% and can achieve a hardness of 50 HRC, its primary characteristic is corrosion resistance. Its impact toughness is slightly inferior to that of 2344. For hard mold components in plastic molds or large plastic molds that require high toughness— sliders, inclined pins, inserts, or even core inserts—where toughness is a requirement—generally favor 2344 mold steel over S136.
S136 is generally used when the mold working environment is relatively humid, or when the injection molding material is acidic, making the mold prone to corrosion or rust. In such cases, we typically choose S136 for the core material. However, S136 is generally not used for sliders, inserts, or tapered pins, as sliding parts made of S136 are prone to scorching.
Regarding the plastic mold with small pillars mentioned by this user—whether 2344 or S136 is better—I would lean toward using 2344.
I’m Wu Dejian, the “King of Mold Steel,” from Dongguan Yuhui Mold Steel. Yuhui Mold Steel is used by three Fortune 500 companies and seven of China’s Top 500 companies, and Kyocera has been sourcing Yuhui Mold Steel for seven consecutive years. If you’re unsure about which mold steel to choose, or if the mold steel you’re currently using results in short mold service life and you don’t know which grade to use, feel free to reach out to me. I’ve helped over 4,000 companies solve complex challenges related to mold material selection, manufacturing, and usage. I’m confident that when it comes to selecting and applying mold steel, I can serve as your chief advisor and help you avoid costly trial-and-error.
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Wu Dejian’s tool steel, the chief of staff of the user, bought everything he had used.